Ramming device comprising a vibration reducing guide cylinder

ABSTRACT

A working device, especially a ramming device for compacting soil, comprises a housing which belongs to an upper mass, and has a working mass which can be linearly driven back and forth with regard to the upper mass. The working mass is linearly guided via a guide cylinder which is fastened to the housing with elastic mobility. The transfer of bounce impacts acting upon the working mass to the upper mass can be effectively reduced by the elastic mobility of the guide cylinder with regard to the housing.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an implement, in particular a ramming devicefor soil compaction.

2. Description of the Related Art

Known rammers of this type are constructed in such a way that an uppermass which accommodates a motor and a crank drive forming a motionconversion device is connected via a spring set to a working mass thatessentially forms a working or compaction plate. The rotational movementproduced by the motor is converted by the crank drive into anoscillating axial movement, which is transmitted via the spring set tothe working plate for soil compaction.

FIG. 6 shows a rammer of this type, for example disclosed by U.S. Pat.No. 3,090,286.

According to FIG. 6, a drive shaft 1 of the rammer is driven by a motor(not illustrated) and, via a pinion 2, drives a crank disk 4 that ismounted in a rammer housing 3 and provided with external toothing.Fitted to the crank disk 4 is a crank pin 5, on which a connecting rod 6is fitted such that it can rotate. At its other end, the connecting rod6 is connected to a guide piston 8 by means of a gudgeon pin 7 such thatit can rotate. The guide piston 8 can be moved axially to and fro, witha piston guide 9 that is fixed to it, within a guide tube 10 in a guidecylinder 11 belonging to the lower mass. This axial directioncorresponds to a vertical or working direction of the implement duringits use.

Arranged on both sides of the piston guide 9 is a spring set 12comprising one or more springs, the springs in each case being supportedon their sides facing away from the piston guide 9 against spring plates13 fixed to the guide tube 10.

The guide tube 10 and the spring plates 13 belong to the working orlower mass of the rammer. A ramming foot (not illustrated in FIG. 6),which serves for soil compaction, can be fitted to the lower mass. Inorder to avoid the ingress of moisture and dirt, the upper mass and thelower mass are connected by an elastic bellows 14.

The guide cylinder 11 guiding the guide tube 10 is rigidly connected tothe housing 3 by means of bolts 15.

During ramming operation, apart from the vibrations brought about by theacceleration of mass in the ramming system, high impact shocks occur onthe rammer as a result of the ramming plate striking the soil—inparticular in the case of very hard, stony soil. This problem is furtherincreased in the case of relatively broad ramming plates and by thefrequent crooked attitudes brought about by this and, respectively, byforces acting obliquely on the ramming plate.

The impact shocks are transmitted by the ramming plate to the guide tubeand the guide cylinder and to the upper mass. As a result, they impairnot only the uniform vibrational acceleration of the upper mass but canalso considerably impair the durability of the parts incorporated in theupper mass, for example the bearings, the toothing systems and themotor. In addition, the impact shocks also have a negative effect withregard to the spring-mounting of the handle.

OBJECTS AND SUMMARY OF THE INVENTION

According to the invention, an implement, in particular a rammer forsoil compaction or a hammer, having an upper mass, which has a drivearranged in or on a housing, having a working mass, which can be drivento and fro linearly by the drive via a motion conversion device and aspring set, and having a guide device, which is fixed to the housing andhas a guide cylinder which guides the working mass linearly relative tothe housing, is defined by the fact that the guide cylinder is fixed tothe housing with elastic mobility, or the guide cylinder itself, givenan otherwise rigid connection, has the desired elastic mobility.

The elastic mobility of the guide cylinder relative to the housingbelonging to the upper mass or, respectively, the elastic mobility ofthe guide cylinder itself, permit effective damping of the impact shocksoccurring at the working mass, in particular of the shocks which do notact in the vertical direction. Viewed from a vibration point of view,although the guide cylinder also belongs to the upper mass, according tothe invention it is decoupled from the remainder of the upper mass, inorder to permit the effective dissipation of force peaks.

In a particularly advantageous embodiment of the invention, one or moreelastic elements are inserted between the housing and the guidecylinder. By means of suitable selection of the elastic elements, thedesired elastic mobility between guide cylinder and housing can beachieved in a straightforward manner. At the same time, it is necessaryto be aware that although the elements on the one hand have to providethe necessary elasticity and a corresponding possible deformationtravel, on the other hand the guide cylinder still has to be connectedrigidly to the housing, in order to ensure the functioning of theimplement.

Therefore, a different embodiment can also be advantageous, in which theguide cylinder consists of a polymer and is connected directly to thehousing without the interposition of elastic elements. Given appropriateconfiguration of a fixing flange provided on the guide cylinder, therequired elasticity is already achieved by means of the polymermaterial.

In a particularly advantageous embodiment of the invention, the guidecylinder is firmly held on the housing by means of a clamping ring. Theclamping ring makes it possible to interpose the elastic elements in asimple way or directly to retain the fixing flange of a guide cylinderconsisting of a polymer.

BRIEF DESCRIPTION OF THE DRAWINGS

These and further advantages and features of the invention will beexplained in more detail below with the assistance of the accompanyingfigures, in which:

FIG. 1 shows a partial sectional illustration of a first embodiment ofthe invention;

FIG. 2 shows a partial sectional illustration of a second embodiment ofthe invention;

FIG. 3 shows a partial sectional illustration of a third embodiment ofthe invention;

FIG. 4 shows a partial sectional illustration of a fourth embodiment ofthe invention;

FIG. 5 shows a partial sectional illustration of a fifth embodiment ofthe invention;

FIG. 6 shows a partial sectional illustration of a known ramming device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 to 5 show various embodiments of the invention in partialsectional illustration. To the extent that the components have alreadybeen described with reference to the known ramming device of FIG. 6,renewed description will be dispensed with. The functioning of all theramming devices illustrated is identical.

The ramming devices according to the invention from FIGS. 1 to 5 aredistinguished by the fact that a guide cylinder is elastically mobilerelative to a housing.

In FIG. 1, a guide cylinder 20 can be seen on which a fixing flange 21is formed.

On the ends of the fixing flange 21 that serve as fixing surfaces 22there bear so-called O rings or round cord rings, which serve as elasticelements 23. The fixing surfaces 22 therefore form contact surfaces withthe elastic elements 23. The elastic elements 23 may surround the guidecylinder 20 completely with a constant radius. However, they can also bedistributed as individual buffers on the circumference of the guidecylinder 20. Some of the elastic elements 23 rest on a stop surface 24belonging to the housing 3, while a clamping ring 25 which is screwed tothe housing 3 and serves as a fixing device engages behind some othersof the elastic elements 23.

As a result of fixing the clamping ring 25 to the housing 3, the elasticelements 23, together with the fixing flange 21 and the guide cylinder20, are firmly connected to the housing 3, but nevertheless a certainelastic mobility remains between the guide cylinder 20 and the housing3. This elasticity is suitable to dissipate force peaks brought about byimpact shocks and, as a result, to protect the upper mass effectivelyagainst shocks.

FIG. 2 shows a different embodiment of the invention, in which, inaddition to the solution of FIG. 1, the clamping ring 25 has anextension 26, which surrounds a further elastic element 27 and pressesit against the guide cylinder 20.

This variant permits a still more rigid connection between the guidecylinder 20 and the housing 3, whilst maintaining the elasticproperties, by which means excessive lateral canting of the guidecylinder 20 with respect to the housing 3 can be avoided.

FIG. 3 shows a third embodiment of the invention, in which the fixingflange 21 known from FIG. 1 has been subdivided into two fixing flanges28, 29 which are independent of each other, each of the fixing flanges28, 29 being supported against elastic elements 23 in only onedirection.

This solution also corresponds in principle to the first embodimentaccording to FIG. 1. However, it opens up the possibility of enlargingthe distance between the fixing flanges 28 and 29 as desired, in orderto increase the rigidity of the connection between the guide cylinder 20and the housing 3.

This idea is developed further in the fourth embodiment of the inventionaccording to FIG. 4, in which it is possible to see two fixing flanges30, 31 which have been drawn far apart from each other. By means of thisarrangement it is possible to prevent lateral canting which may possiblyoccur under extreme loads in the case of the previously describedexemplary embodiments.

In the fourth embodiment according to FIG. 4, instead of the previouslyshown round cord rings 23, elastic elements 32 are also shown, whichhave been adapted specifically for the intended application as moldedrubber parts to be prepared separately. In the embodiment shown in FIG.4, the elastic elements 32 cover not only the fixing surfaces of thefixing flanges 30, 31 but also the circumferential surfaces, as a resultof which in particular lateral shocks can be intercepted better.

A fifth embodiment is illustrated in FIG. 5.

The rammer shown there has a guide cylinder 33 of a polymer material.The polymer is already sufficiently elastic that, given an otherwiserigid connection between the guide cylinder 33 and the housing 3, thedesired elastic mobility can be achieved. For this purpose, the guidecylinder 33—in a way similar to the fourth embodiment according to FIG.4—has two fixing flanges 34, 35, which should be at not too small adistance from each other.

In order to increase the elasticity, recesses 36 can be formed in thefixing surfaces of the fixing flanges 34, 35, said recesses reducing theeffective fixing surfaces and therefore increasing the local surfacepressure, an increase in the elasticity within the fixing surfaces beingachieved at the same time.

In addition to the advantageous action of the guide cylinder 33 withregard to the damping of impact shocks, considerable advantages in termsof weight also result. Furthermore, the production of a polymer part ofthis type is simpler than the production of a comparable part of metal.

What is claimed is:
 1. An implement, in particular a rammer for soilcompaction or hammer, comprising: an upper mass, which has a drivearranged in or on a housing; a working mass, which can be driven to andfro linearly by the drive via a motion conversion device and a springset; and a guide device, which is fixed to the housing and which has aguide cylinder which guides the working mass linearly relative to thehousing; wherein the guide cylinder is fixed to the housing so as to beelastically movable relative thereto.
 2. The implement as claimed inclaim 1, wherein the guide device has a fixing device which fixes theguide cylinder to the housing.
 3. The implement as claimed in claim 2,wherein the guide cylinder has a fixing surface which extendsessentially parallel to a stop surface provided on the housing andbehind which the fixing device engages.
 4. An implement, in particular arammer for soil compaction or hammer, comprising: an upper mass, whichhas a drive arranged in or on a housing; a working mass, which can bedriven to and fro linearly by the drive via a motion conversion deviceand a spring set; and a guide device, which is fixed to the housing andwhich has a guide cylinder which guides the working mass linearlyrelative to the housing; wherein the guide cylinder is fixed to thehousing with elastic mobility, or the guide cylinder itself, given anotherwise rigid connection, has elastic mobility, and wherein at leastone elastic element is inserted between the housing and the guidecylinder.
 5. The implement as claimed in claim 4, wherein the guidedevice has a fixing device which fixes the guide cylinder to the housingand wherein at least one elastic element is inserted between the guidecylinder and the fixing device.
 6. The implement as claimed in claim 4,wherein the elastic element or element consists or consist of aresilient material or of a polymer.
 7. The implement as claimed in claim4, wherein the guide cylinder has at least one contact surface with oneof the elastic elements, said contact surface extending essentiallyparallel to a stop surface provided on the housing.
 8. The implement asclaimed in claim 4, wherein the guide cylinder has at least one contactsurface in contact with one of the elastic elements, said contactsurface extending essentially perpendicular to a stop surface providedon the housing.
 9. An implement, in particular a rammer for soilcompaction or hammer, comprising: an upper mass, which has a drivearranged in or on a housing; a working mass, which can be driven to andfro linearly by the drive via a motion conversion device and a springset; and a guide device, which is fixed to the housing and which has aguide cylinder which guides the working mass linearly relative to thehousing; wherein the guide cylinder is fixed to the housing with elasticmobility, or the guide cylinder itself, given an otherwise rigidconnection, has elastic mobility, wherein the guide cylinder has afixing device which fixes the guide cylinder to the housing, wherein theguide cylinder has a fixing surface which extends essentially parallelto a stop surface provided on the housing and behind which the fixingdevice engages; and wherein the fixing surface has elastic properties.10. The implement as claimed in claim 9, wherein the fixing devicecomprises a clamping ring.
 11. The implement as claimed in claim 10,wherein the guide cylinder consists of a polymer.
 12. An implement, inparticular a rammer for soil compaction or hammer, comprising: an uppermass which has a drive arranged in or on a housing; a working mass whichcan be driven to and fro linearly by the drive via a motion conversiondevice and a spring set; and a guide device which is fixed to thehousing and which has a guide cylinder which guides the working masslinearly relative to the housing; wherein the guide cylinder is rigidlyconnected to the housing and consists of a polymer such that it iselastically movable relative to the housing.
 13. The implement asclaimed in claim 12, wherein the guide cylinder has a fixing surfacewhich extends essentially parallel to a stop surface provided on thehousing and behind which a fixing device engages.
 14. The implement asclaimed in claim 13, wherein the fixing surface has elastic properties.15. The implement as claimed in claim 13, wherein the fixing devicecomprises a clamping ring.